QAMISHLI, Syria (Reuters) – The U.S.-backed Syrian Democratic Forces (SDF) began an assault against the final Islamic State enclave in eastern Syria on Saturday, aiming to wipe out the last vestige of the jihadist group’s “caliphate” in the SDF’s area of operations.

President Donald Trump, who is planning to pull U.S. forces out of Syria, said on Wednesday he expected an announcement as early as next week that the U.S.-led coalition operating in support of the SDF had reclaimed all the territory previously held by the jihadist group.

The enclave, close to the Iraqi border, comprises two villages. Islamic State also still has territory in the part of Syria that is mostly under the control of the Russian- and Iranian-backed Syrian government.

Mustafa Bali, head of the SDF media office, told Reuters the aim of the assault was to “eliminate the last remnants of the terrorist organization” and called it the “last battle”.

He later wrote on Twitter that the battle had started and the enclave would “be cleared soon”.

Bali told Reuters that in the last 10 days SDF fighters had handled the battle “patiently” as more than 20,000 civilians were evacuated from the besieged enclave.

The SDF, spearheaded by the Kurdish YPG militia, has driven Islamic State out of a swathe of territory in northern and eastern Syria over the last four years.

Islamic State leader Abu Bakr al-Baghdadi declared the group’s “caliphate” in 2014 in territory stretching across Iraq and Syria. But the group lost its two main prizes – the Syrian city of Raqqa and Iraq’s Mosul – in 2017.

After capturing Raqqa, the SDF advanced southwards into Deir al-Zor province, attacking the jihadists in territory on the eastern bank of the Euphrates River.

The remaining Islamic State territory in Syria is west of the Euphrates.

Trump said in December he was pulling all 2,000 U.S. troops out of Syria, saying the battle against Islamic State there was almost won.

But a top U.S. general said on Tuesday the group would pose an enduring threat following the U.S. withdrawal, as it retained leaders, fighters, facilitators and resources that would fuel a menacing insurgency.

The Wall Street Journal reported on Friday that the U.S. military was preparing to withdraw from Syria by the end of April.

A U.S. official confirmed that target date to Reuters, saying the withdrawal included a pull-out from the U.S. military base at Tanf, near the Syrian border with Iraq and Jordan.